Experimental Hybridizing 79 
The question may be asked whether this method of account- 
ing for the results can be referred to the changes that take place 
in the chromosomes of the germ-cells. The hypothesis de- 
mands that the contrasted characters come into relation with 
each other, and the union of the chromosomes might suggest 
such a possible combination. After uniting, the fused char- 
acters must be halved again (quantitatively not qualitatively), 
and the reduction division might suggest a possible method of 
accomplishing this result. On the other hand, there is no 
apparent need to assume such a complicated mechanism to 
bring about the union of the characters in the same cell, nor 
for their subsequent separation. Moreover, by referring the 
process to the chromosomes, we introduce the further assump- 
tion that the characters of the cell are contained only in those 
bodies — an assumption that is not itself established. For the 
present, therefore, it seems premature to connect these results 
definitely with any known change in the germ-cells, and the 
same statement holds also, as we have seen, for the alternative 
assumption of pure germ-cells. 
Until we know more of the way in which characters are 
represented in the germ-cells, we can only offer purely specula- 
tive views of what we suppose might take place in order to give 
the Mendelian results. The formule that we use are merely 
symbols for handling these results. The fact that the char- 
acters that “‘Mendelize” are different types or permutations of 
the same characters suggests that they may represent stereo- 
metric relations of the material basis of the characters, i.e. of 
the molecules representing them. Thus we might represent 
the characters gray and white in the hybrids as right- and left- 
handed forms of the same molecule, and indicate this by GW 
and WG. Such germ-cells meeting each other would give — 
cw, {cw {we 
eee 
and these might be taken as representing the three Mendelian 
groups. Interesting as such a speculation might be, could we 
